This application is related to Japanese Patent Application No. 2001-111828 filed on Apr. 10, 2001, whose priority is claimed under 35 USC xc2xa7119, the disclosure of which is incorporated by reference in its entirety.
1. Field of the Invention
The present invention relates to a toner for electrophotography. More particularly, it relates to a toner for full-color electrophotography which is used for image-forming apparatuses using so-called electrophotographic techniques such as electrostatic copiers, laser beam printers and the like.
2. Description of Related Art
Many electrophotographic techniques have been conventionally known, which, in general, form electrical latent images on photoconductors by various means with use of photoconductive materials, develop the latent images with use of toners, transfer toner images onto recording media such as paper as the need arises, and then fix the toner images by heat, pressure or a vapor of a solvent to obtain copies.
In the electrophotography, full-color images are made by overlaying toners of three colors, i.e., yellow (Y), magenta (M) and cyan (C) or of four colors, i.e., the three colors plus black. More particularly, charging, exposure, development and transfer are repeated for every toner to form toner images of a plurality of colors of toners on a recording medium and fixing the toner images by fusing and mixing (mixing color) the toner colors.
Various techniques and apparatuses have been developed for the last step in the full-color image formation, i.e., the step of fixing toner images onto recording media such as paper.
These techniques can prevent offset effectively. However, the toners have a high elasticity since they contain a lot of crosslinked acid components and polymeric components. Accordingly, the toners do not form flat surfaces on which they are fixed in the range of relatively low temperatures, which is a problem from the viewpoint of color reproducibility as full-color toners.
Further, Japanese Unexamined Patent Publication Nos. HEI 4(1992)-12367 and HEI 5(1993)-165252 propose toners having a binding resin of a polyester containing cyclohexane dimethanol as an essential polyol component. However, these publications do not give consideration as to how to use the toners for exhibiting the characteristics of the resin better. Thus, even if toner images formed using these toners are fixed by an ordinary fixing method, sufficient color mixing is not performed. At present, is not obtained yet a toner which can provide high-quality color images with a smooth surface with wide-ranged color reproduction in an increased fixing temperature range without image deterioration due to oil.
Thus, the present invention has been made in view of the above-mentioned problems, and an object of the present invention is to provide a toner for electrophotography which has a sufficient color mixing property and transparency and which can provide high-quality color images having a flat surface and free of deterioration due to oil, with a wide color reproducibility in a wide fixing temperature range.
The present invention provides a toner for electrophotography comprising: a coloring agent and a binding resin comprising a polyester resin constituted of cyclohexanedimethanol as an essential polyol component, wherein the toner has, at 110xc2x0 C., a storage elastic modulus of 3xc3x97104 Pa or less and a loss elastic modulus of 6xc3x97104 Pa or less, and, at 150xc2x0 C., a storage elastic modulus of 1xc3x9710 Pa or more and a loss elastic modulus of 1xc3x97102 Pa or more.
These and other objects of the present application will become more readily apparent from the detailed description given hereinafter. However, it should be understood that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description.